Hinge seams for dryer felts and the like



g- 15, 1967 T. HINDLE ETAL 3,335,844

HINGE SEAMS FOR DRYER FELTS'AND THE LIKE Filed July 5, 1966 2 Sheets-Sheet 1 g- 15, 1967 T. HINDLE ETAL HINGE SEAMS FQR DRYER FELTS AND THE LIKE 2 Sheets-Sheet 2 Filed July 5, 1966 vm @w @n i am mm 34 Y\ V \S 7//Vk/ c /7 z /7/ /AM Or w; LNG l. OF

nd E I United States Patent 3,335,844 HINGE SEAMS FUR DRYER FELTS AND THE LIKE Thomas Hindle and John R. Hindle, Blackburn, England,

assignors to Scapa Dryers Limited, Blackburn, England, a company of the United Kingdom of Great Britain and Northern Ireland Filed July 5, 1966, Ser. No. 562,629 Claims'priority, application Great Britain, July 7, 1965, 28,773/ 65 6 Claims. (Cl. 198193) ABSTRACT OF THE DISCLOSURE A clipper seam uniting the ends of a papermakers dryer felt, wherein interleaved series of wire loops, attached to the respective ends of the felt, are united by a pintle device, and the pintle device comprises two parallel wires, each of which nonrotatably engages the loops of one set respectively, while the wires themselves make rolling contact with each other, thereby minimizing twisting of the wires and wear between the wires and the loops.

The invention relates to a hinge seam for use in an endless travelling felt, conveyor band or the like, but is concerned more particularly with a seam for an endless dryer felt as used for example in paper-making, boardmaking, and similar machinery.

The invention relates to that type of hinge seam known in the trade as a clipper seam, which comprises a number of side-by-side wire loops or eyes extending from the two edges to be joined, with the loops or eyes on one edge staggered and interleaved with respect to those on the other edge, a pintle wire being passed through the interleaved loops, across the width of the felt, to form the hinge pivot.

When these felts are in use, travelling over and under successive cylinder and/ or guide rolls in a paper or board machine, the clipper seam is compelled to flex in reverse directions, sometimes to a substantial extent as when the felt passes over or under the small-diameter guide-rolls of the paper-machine. During this flexing, the wire loops afiixed to one end of the felt swing, relatively to the wire loops afiixed to the other end of the felt, in opposite directions around the axis of the pintle-wire, using such wire as a fulcrum or centre. The tendency is for the pintle wire to become fixed in one set of loops, with the other set swinging around it, and observation shows that it is a matter of mere chance as to which of the two sets of loops is the fixed one. What is more important is, as observation again shows, that the pintle-wire becomes fixed in one set of .loops along some parts of its length (length of the wire being width-wise of the felt) and fixed in the other set of loops for other parts of its length. This selective gripping of the pintle-wire by the two sets of wire loops means that at some point or points in its length the pintle-wire is subjected to reverse twisting, which leads to rapid fracture of the pintle-wire or of some of its component wires if of cabled or plaited form. In some cases this may result in a premature failure of the clipper seam, which becomes apparent all to late by the felt, which may be running at over 2,500 feet per minute, collapsing into the paper machine basement and, during its descent possibly damaging other dryer felts on the same machine.

In addition to the above-described reverse twisting action in the pintle wire, those wire loops of either set which turn on the pintle wire cause severe surface abrasion both of the pintle-wire (and/ or its protective covering if any) and of the wire loops themselves. This surface 3,335,844 Patented Aug. 15,. 1 967 abrasion renders the pintle-wire much less able to withstand the said reverse twisting action and, in combination with such action, seriously decreases the useful life of the clipper-seam whilst tending during its life to precipitate disastrous failure.

This problem of the relatively short life of the clipper seam has become accentuated of late owing to the much longer life obtainable from modern dryer felts especially When'they are made with a high percentage of synthetic fibre inter-mixed with the cotton or are made Wholly of synthetic fibre.

Attempts have already been made to lengthen the life of a clipper seam and for this purpose modified forms of pintle-wire have been proposed, with some advantage. According to one such proposal a stranded steel wire is provided with a protective coating of nylon or other synthetic plastic which has greater resistance to the surface abrasion caused by the wire loops than has the unprotected stranded wire normally used. Nevertheless, these protective covering although more resistant to abrasion do not in any useful degree make the pintle-wire more resistant to the above-described repeated reverse twisting action and the useful life of such covered pintlewires is still severely limited when compared with the extended life provided by a modern dryer felt.

It is the object of the present invention to provide still further improvements in clipper seams whereby the said reverse twisting of the pintle wire is avoided altogether and abrasion between pintle-wire and the wire loops due to relative movement therebetween is thereby avoided completely.

According to this invention, a clipper seam is characterised in that two pintle-wires are provided, through the interleaved sets of loops and maintained in rolling contact with each other under the tension in the felt. For this purpose the wire loops on the edges of the felt are elongated so as to allow of the two side-by-side pintlewires being threaded there through. The shape and size of the loops will be such as to prevent the said pintle-wires moving to relative positions where they would not be in rolling contact under stress from the tension of the felt.

According to a further feature of the invention, the shape of the loops in side elevation and the cross-sectional shape of the pintle-wires are such that there is a Wedging action between each wire and the respective set of loops, this action tending to hold the wire firmly in the loops non-rotatably so that the wholly of the flexing or bending movement between the two ends of the felt takes place between and along the whole length of the pintle-wires only.

It has been found that with such an arrangement each of the said two pintle-wires becomes locked to the set of wire loops whose extremities embrace it, this locking elfect being uniform along the whole length of the wire, whereby reverse movement between different parts of a wire is prevented. Also, as each wire becomes fixed to the loops which contact it there is no repeated movement between the wire and the loops, so that abrasive wear of the pintle-wire and/ or the wire loops which would result therefrom is completely prevented. What movement there is between abutting surfaces, namely between the peripheries of the two wires, being in the nature of a rolling movement rather than a sliding movement, abrasive wear is reduced to the minimum.

The necessary elongated formation of the loops to re ceive the two side-by-side pintle-wires may be the result of these loops being made to an increased length or, in a less preferred arrangement, such formations may be the result of the loops being secured to the felt nearer to the edge of the felt than is normal so as to leave a larger part of each loop available for interleaving with those of the other set.

The invention will now be described further, by way of example only, with reference to the accompanying drawing in which:

FIG. 1 is a diagrammatic plan view of a portion of a paper-machine dryer felt, showing a clipper seam according to the present invention;

FIG. 2 is a section on the line 22 of FIG. 1; and

FIGS. 3 and 4 are diagrammaticillustrations of alternative embodiments of the invention.

The conventional clipper seam is made by inserting wire clips at regularly spaced intervals along the thicker selvedge of each of two strips of tapered webbing of the character of that disclosed in British patent specification 847,646. One strip of webbing wit-h the clips attached is stitched to the underside of each end of the felt in such a manner that when the two sets of clips are engaged they provide a continuous passage through the interleaved eyes, and the ends of the felt form a closelybutted joint just beyond the longer clinching toes of one set of clips. The seam is completed by the introduction of a flexible hinge or pintle Wire through the interleaved eyes of the clips.

The seam constructed in accordance with the invention and as illustrated in FIGS. 1 and 2 is made in a similar manner to that above described except that, after the two sets of clips 24, 26 are engaged, two flexible hinge or pintle-wires 44 and 46 are threaded through the interleaved eyes of the clips. The lengths of leg of the clips are increased slightly as compared with conventional clips to accommodate the two wires side-by-side and the shape and size of the hooks are such that they keep the two wires in rolling contact under the tension of the dryer felt.

The invention is not limited to wire loops having a semi-circular outer end therto, since in some circumstances the loops may be of a different form. Thus, for example, the loops may be made with a V formation at the outer ends as shown in FIG. 5, and as the pintle-wire (especially if coated with a synthetic sheath or braid as is known, and with or without a synthetic dope applied to such sheath or braid) becomes forced into the V loops there is a compression .of the sheath into the V formations which holds the pintle-wire non-rotatably.

In an alternative arrangement (see FIG. 4), the pintlewire 62, 64, instead of being made to circular cross section, are made to a non-circular cross-section, having an arcuate surface 62a, 64a where they will abut each other longitudinally and a non-arcuate surface 62b, 64b where they engage a corresponding shape in the loops.

As is well known in the art, the wire clips may be clinched directly in the two ends of the dryer felt or, alternatively, may be clinched along one edge of a narrow webbing, one piece of which is then securely sewn to each end of the dryer felt, with the same general effect. Furthermore, although we have illustrated the use of tapered webbing in the construction of the clipper seam, any suitable type of webbing such as, for example, four layer webbing of uniform thickness or two thicknesses of two-layer webbing may be employed.

What we claim is:

1. A clipper seam for an endless felt comprising a plurality of side-by-side wire loops extending from the edges to be joined, the loops on one edge being staggered and interleaved with respect to those on the other, and

two pintle wires through the interleaved sets of loops, the said wires being maintained in rolling contact with each other under the tension in the felt, characterized in that the shape of the loops in side elevation and the crosssection of the pintle wires are such that there is a wedging action between each wire and the respective set of loops thereby to hold the wire non-rotatably in such loops.

2. A clipper seam as claimed in claim 1, wherein each pintle wire has a non-arcuate surface portion thereto and the respective loops a complementary region to receive such portion.

3. A clipper seams as claimed in claim 2, wherein the loops have a V-forrnation at the outer ends thereof.

4. A paper making or like felt including a clipper seam which comprises a plurality of side-by-side wire loops extending from the edges to be joined, the loops on one edge being staggered and interleaved with respect to those on the other, and two pintle wires through the interleaved sets of loops, the said wires being maintained in rolling contact with each other under the tension in the felt, characterized in that the shape of the loops in side elevation and the cross-section of the pintle wires are such that there is a wedging action between each wire and the respective set of loops thereby to hold the wire nonrotatably in such loops.

5. A clipper seam comprising side-by-side elongated wire loops extending outwardly from the edges to be joined, the loops on one edge being staggered and interleaved with respect to those on the other, a passage defined by the said interleaved loops, the said passage being of generally oval transverse cross-section of which the major axis lies in the direction of the loops, and two pintle wires in side-by-side disposition in the said passage, the said pintle wires being maintained in rolling contact with each other under the tension in the felt, characterized in that the shape of the loops in side elevation and the crosssection of the pintle wires are such that there is a wedging action between each wire and the respective set of loops thereby to hold the wire non-rotatably in such loops.

6. A paper maker felt including a clipper seam comprising two sets of side-by-side loops respectively, extending outwardly from the edges to be joined, the loops on one edge being staggered and interleaved with respect to those on the other, a passage defined by the said interleaved loops, the said passage being of generally oval transverse cross-section of which the major axis lies in the direction of the loops, and two pintle wires in sideby-side disposition in the said passage, the said pintle Wires being maintained in rolling contact with each other under the tension in the felt characterized in that the shape of the loops in side elevation and the crosssection of the pintle wires are such that there is a wedging action between each wire and the respective set of loops thereby to hold the wire non-rotatably in such loops.

References Cited UNITED STATES PATENTS 1,698,100 1/1929 Lee 24-31 2,587,053 2/1952 Lopez 24-39 X 3,225,900 12/1965 MacBeam et al. 198l93 EVON C. BLUNK, Primary Examiner.

R. I. HICKEY, Assistant Examiner. 

1. A CLIPPER SEAM FOR AN ENDLESS FELT COMPRISING A PLURALITY OF SIDE-BY-SIDE WIRE LOOPS EXTENDING FROM THE EDGES TO BE JOINED, THE LOOPS ON ONE EDGE BEING STAGGERED AND INTERLEAVED WITH RESPECT TO THOSE ON THE OTHER, AND TWO PINTLE WIRES THROUGH THE INTERLEAVED SETS OF LOOPS, THE SAID WIRES BEING MAINTAINED IN ROLLING CONTACT WITH EACH OTHER UNDER THE TENSION IN THE FELT, CHARACTERIZED IN THAT THE SHAPE OF THE LOOPS IN SIDE ELEVATION AND THE CROSSSECTION OF THE PINTLE WIRES ARE SUCH THAT THERE IS A WEDGING ACTION BETWEEN EACH WIRE AND THE RESPECTIVE SET OF LOOPS THEREBY TO HOLD THE WIRE NON-ROTATABLY IN SUCH LOOPS. 